.TH std::ranges::views::values,std::ranges::values_view 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::ranges::views::values,std::ranges::values_view \- std::ranges::views::values,std::ranges::values_view

.SH Synopsis
   Defined in header <ranges>
   template< class R >                                     \fB(1)\fP \fI(since C++20)\fP
   using values_view = ranges::elements_view<R, 1>;
   namespace views {

       inline constexpr auto values = ranges::elements<1>; \fB(2)\fP \fI(since C++20)\fP

   }

   Takes a view of tuple-like values (e.g. std::tuple or std::pair), and produces a
   view with a value-type of the second element of the adapted view's value-type.

   1) An alias for ranges::elements_view<R, 1>.
   2) RangeAdaptorObject (and also RangeAdaptorClosureObject). The expression
   views::values(e) is expression-equivalent to
   values_view<views::all_t<decltype((e))>>{e} for any suitable subexpression e.

.SH Notes

   values_view can be useful for extracting values from associative containers, e.g.

 std::map<int, std::string> map{{1, "alpha"}, {2, "beta"}};
 for (auto const& value : std::views::values(map))
     std::cout << value << ' ';
 // prints: alpha beta

.SH Example


// Run this code

 #include <iostream>
 #include <map>
 #include <ranges>

 int main()
 {
     const auto list = {std::pair{1, 11.1}, {2, 22.2}, {3, 33.3}};
     std::cout << "pair::second values in the list: ";
     for (double value : list | std::views::values)
         std::cout << value << ' ';

     std::map<char, int> map{{'A', 1}, {'B', 2}, {'C', 3}, {'D', 4}, {'E', 5}};
     auto odd = [](int x) { return 0 != (x & 1); };
     std::cout << "\\nodd values in the map: ";
     for (int value : map | std::views::values | std::views::filter(odd))
         std::cout << value << ' ';
     std::cout << '\\n';
 }

.SH Output:

 pair::second values in the list: 11.1 22.2 33.3
 odd values in the map: 1 3 5

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

      DR    Applied to            Behavior as published              Correct behavior
   LWG 3563 C++20      keys_view is unable to participate in CTAD  views::all_t removed
                       due to its use of views::all_t

.SH See also

   ranges::keys_view     takes a view consisting of pair-like values and produces a
   views::keys           view of the first elements of each pair
   (C++20)               \fI(class template)\fP (range adaptor object)
   ranges::elements_view takes a view consisting of tuple-like values and a number N
   views::elements       and produces a view of N^th element of each tuple
   (C++20)               \fI(class template)\fP (range adaptor object)
   slice                 BLAS-like slice of a valarray: starting index, length, stride
                         \fI(class)\fP
